1. Technical Field
The present invention relates to a developing device and an image forming apparatus.
2. Related Art
An image forming apparatus such as a laser beam printer is provided with a photo conductor as one example of a latent image supporting body for supporting a latent image, and a developing device which develops the latent image supported on the photo conductor by toner. In order to develop the latent image supported on the photo conductor, the developing device has a developing chamber, which has an opening and contains toner, and a developing roller which is provided facing the opening and supports toner. The latent image supported on the photo conductor is developed by the toner supported on the developing roller.
In the developing chamber which contains toner, a toner supply roller is disposed. The supply roller comes into contact with the developing roller so as to supply toner to the developing roller, and also, scrape off remaining toner from the developing roller after development. A regulating blade comes into contact with the developing roller so as to regulate the thickness of toner layer supported on the developing roller. A seal member comes into contact with the developing roller at a position passed over a development position, so as to allow movement of toner remaining on the developing roller into the developing chamber and regulate movement of toner in the developing chamber to the exterior of the developing chamber.
In JP-A-2005-292788, there is disclosed a developing device in which a developing roller for supporting toner and a seal member which comes into contact with the developing roller at a position passed over a development position in order to prevent leakage of toner by coming into contact with the developing roller are mounted on a developing chamber, and also, a support member for supporting the developing roller and the seal member, and a biasing member for biasing the seal member against the developing roller are provided.
In such a developing device, there is a case where as a printing time or the number of printing sheets increases, fixation of toner to a nip portion of the seal member and the developing roller occurs. Fixation of toner to the seal member becomes a cause of filming of the developing roller, so that a stripe is generated in an image, or leakage of toner from a seal portion is generated.